Lazy eye not necessarily crossed or wandering eyes

Andrea K. Walker, The Baltimore Sun

Lazy eye is often mistaken for eyes that cross or wander, but some patients with the disorder don't show these symptoms. Dr. Lisa Abrams, a pediatric ophthalmologist at Katzen Eye Group, talks about how lazy eye is diagnosed, who gets it and how it is treated.

What is lazy eye?

"Lazy eye," amblyopia, is often misinterpreted as an eye that crosses or wanders. These conditions can be associated with "lazy eye," but the real meaning is an eye that does not see as well as it should. When an eye has a high refractive error (nearsightedness, farsightedness or astigmatism) or is misaligned (strabismus — crossing or wandering) at an early age, the child will use the other eye, which has clearer vision. Over time, this becomes a vicious cycle, the stronger eye is used more and the weaker eye is used less so it becomes even weaker. Amblyopia can also be caused by a structural problem in the eye, like congenital cataracts or a droopy eyelid that prevents the eye from having a clear image.

Who is most likely to get lazy eye?

Amblyopia occurs in approximately 1 in 20 children and is most common in children who have a family history of amblyopia or strabismus. It does not necessarily have to be present in a parent, but if present in a relative the child is at higher risk. Amblyopia is also more common in children with other medical conditions such as prematurity and inherited eye diseases.

What are the symptoms of lazy eye?

If a child does not have crossing or wandering eyes, there may be no outward signs of amblyopia. Unless the stronger eye is covered, the child may not even realize that he or she is not seeing well out of the weaker eye. Often, vision screenings at school or the pediatrician's office can detect the problem. If there is a family history of amblyopia, strabismus, early glasses wear or any medical risk factors, then a comprehensive dilated exam may be suggested. Amblyopia does NOT cause problems such as letter reversals or difficulty learning to read.

How do you treat lazy eye?

Amblyopia is most often treated first with glasses. Therapy's goal is for the child to use the weaker eye to make it stronger, just as you would lift weights to make a muscle stronger. Occlusion therapy, patching of the stronger eye, is commonly used. This is when a patch is used to cover the eye for a prescribed length of time each day. An alternative to patching is pharmacologic penalization, which is the use of Atropine sulfate drops to blur the stronger eye so that the amblyopic eye is favored. Both methods work well, but each has its own advantages and disadvantages.

Patching is usually recommended for at least one hour per day or sometimes up to six hours per day. The problem with patching is that some children will not leave the patch on or will "cheat" by looking around the patch.

The advantage of the drops is that they can be given as infrequently as once a week or two or three days a week, which is more common. Once the drop is administered, there is no way to "cheat" since the drops blur the near (reading) vision in the stronger eye and the child learns to use the weaker eye. The drops can cause light sensitivity due to pupillary dilation.

Other less common therapies include blurring the stronger eye with glasses, or placing a "filter" on the glasses lens of the stronger eye. Surgery is NOT a treatment for amblyopia. Surgery may be used to treat strabismus, which may be contributing to amblyopia, but surgery does not preclude the need for patching or administering drops.

What are the risks of lazy eye if untreated?

Amblyopia tends to worsen if not treated. As the weaker eye is used less, the visual acuity becomes progressively worse making treatment more challenging. In some cases, the eyes will develop strabismus if the amblyopic eye deteriorates significantly. Amblyopia is only treatable until the visual system finishes developing, which is typically between the ages of 8 to 10. It is important to begin treatment early and to continue treatment until instructed.

Can lazy eye lead to blindness?

Dense amblyopia can result in legal blindness if untreated.

Why won't lazy eye go away on its own?

Once amblyopia develops, it will not resolve on its own because the brain's visual systems will not develop properly. The brain becomes accustomed to the blurred image seen by the weak eye and can't interpret a clear image without additional treatment. Therapy is most effective if begun early and followed through until at least age 10. With good compliance, most patients achieve improvement in vision and some may outgrow glasses.